Chemistry and Beauty


espite the beauty of Chemistry, which continues to successfully astonish us with new inventions to meet our daily needs, it remains a double-edged weapon. For example, women pay a lot of attention to their looks without considering the potential harm of using some products such as hair dye and nail polish for a long time, the result of which may be the destruction of their beauty, or even illness.

Hair Dye Chemistry

The melanin dye that gives the hair its natural color is divided into two types: eumelanin and pheomelanin. Eumelanin gives a darker hair color, like black and brown, while pheomelanin gives lighter colors; differences in the concentration of these two dyes result in different hair colors.

When you dye your hair, you either choose permanent hair dye (oxidative) or temporary pigment. Permanent dyes are produced from a primary intermediate material known as Paraphenylenediamine (PPD); this substance produces brownish shadows when exposed to oxidizing agents. For this reason, another highly oxidizing substance is added to most hair dyes. That would be hydrogen peroxide, which oxidizes the melanin pigment, making its particles colorless if the dying process lasts for a long time.

The hair dying process needs chemical reactions that occur in the presence of an alkaline medium; as a result, ammonia is added to dying compounds. Ammonia swells the scalp, which helps the dye particles flow into hair follicles through inner and outer melanin pigments, resulting in a permanent color. As ammonia has harmful effects on human health, some companies have produced dyes free of ammonia, using other alternatives, such as ethanolamine; unfortunately, the dye effect fades with time.

As for temporary pigments, they are the contrary of permanent dyes; they place the dye particles on the outer layer of melanin only and do not penetrate into the hair follicles. Besides that, the presence of a small amount of oxidizing agents, such as hydrogen peroxide, ensures finalizing the hair dying process in an alkaline medium; this amount makes the dye temporary. Temporary dyes do not contain ammonia or its alternatives, so it fades after applying shampoo repeatedly on hair.

Hair dying has harmful effects; it destroys the hair on the long run and, in some cases, may lead to severe sensitivity resulting in some deaths. Some studies discovered a relation between using hair dyes and increased rates of bladder cancer; thus, it is preferable to use gloves while applying dyes to hair.

Nail Polish Chemistry

Nail polish consists of nitrocellulose, in addition to other chemicals that give it its different colors—such as green chromium oxide, titanium dioxide, ferric oxide, manganese, mica, ultramarines—as well as UV rays filters in order not to change its color when exposed to sunlight. Moreover, some thickening agents* are added to keep the luminous particles shinny for a long time inside the container.

The danger of using nail polish lies in the presence of so-called triple toxins: formaldehyde, toluene, and dibutyl phthalate. Formaldehyde gives a strong volume to the nail polish, toluene gives it its soft appearance, and dibutyl phthalate prevents it from dryness.

Formaldehyde is known to be a carcinogenic substance; while toluene reduces blood cells, destroys the liver, and causes congenital malformations in fetuses. What is strange about nail polish is that it may harm you severely when you try to remove it; that happens because we use acetone to remove nail polish. Acetone inhalation leads to eye redness, pulmonary congestion, and dyspnea; frequent exposure to acetone causes chronic inflammation of the trachea and difficulty in breathing.

It is worth mentioning that there are nail polish removers that are acetone free, but contain other toxic chemicals, such as ethyl acetate, which is similar in its toxicity to acetone and toluene. There is also methanol, which is more toxic than acetone; it causes coughing, dizziness, vision disorder, blindness, or coma, according to the degree of inhalation or swallowing.

These materials do not only harm user health, but also harm the health of the workers at nail polish companies and beauty center employees, because they are exposed to these substances for long times. Recently, a more advanced type of nail polish emerged; synthetic gel nail polish lasts for several weeks, equating three times traditional nail polish is applied. Every layer of the polish is braced with UV rays, increasing the risk of cancer.

To reduce potential side effects of using nail polish, we recommend using water-based nail polish, as it does not release any toxins.

Last but not least, research and studies will continue to study the chemicals that humans use on daily bases, in an attempt to find alternatives less harmful on human health while meeting our needs. Knowing their side effects, we should reduce our usage of these materials to maintain good health and avoid illness.

*Thickening agents: Substances when added to any water mixture increase its viscosity without any fundamental change in its other properties.


*Published in SCIplanet Printed Magazine, Winter 2018 Issue.

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SCIplanet is a bilingual edutainment science magazine published by the Bibliotheca Alexandrina Planetarium Science Center and developed by the Cultural Outreach Publications Unit ...
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